Image sink example
image_sink is an example program that shows how to receive an image from the robot, modify it and send it to another port (so that it can be displayed with yarpview).
You can find image_sink the icub repository, under vvv/nat/image_sink. Run it for example:
image_sink --name /mysink
The program creates two ports /mysink/in and /mysink/out. Connect /james/cam/left to /mysink/in and /mysink/out to a yarpview input port, like this:
yarp connect /james/cam/left /mysink/in mcast
yarp connect /mysink/out /your-yarpview/in